Red tide study documents severity of blooms in hopes of identifying levels of risk in future outbreaks

A recent study uses six decades of red tide data along Florida’s west coast to compare the strength of algal blooms over the years, creating an index of bloom severity.

National and regional scientists looked at cell counts of the red tide organism, Karenia brevis, between 1953 and 2019, as well as reports of respiratory irritation from 2006.

Courtesy of Research Article.



This is a map of the study area.

The recently published article in the peer-reviewed journal PLOS One, shows that red tide blooms most often occur from Sanibel Island to Tampa Bay between September and January, usually forming in August and continuing throughout winter, October and November being the most frequent months. frequently impacted.

“Red tide blooms are described as hitting southwest Florida nine out of ten years,” study lead author Richard Stumpf, an oceanographer at NOAA-NCCOS, said in a news release. .

“But not all flowers are created equal. Some last longer, some cause more respiratory irritation. Others affect a smaller area or produce less irritation. In trying to protect public health and local economies, we found that we really needed a better way to assess blooms and the threat they pose.

Scientists from the National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science, the Gulf of Mexico Coastal Ocean Observing System, Texas A&M University, and the Florida Fish and Wildlife Conservation Commission-Fish and Wildlife Research Institute contributed to the ‘study.

They found that the most extensive red tide along Florida’s southwest coast occurred in 2018. Also that year, the respiratory irritation index in Manatee and Sarasota counties was the highest ever recorded.

Research shows that wind direction is important to the amount of respiratory irritation. For example, years with severe blooms, such as 2006, 2012, and 2018, caused noticeable respiratory irritation, while other years with blooms, such as 2008, 2009, 2011, 2013, 2014, had almost no no respiratory impact due to more frequent than usual onshore winds. .

Bar graph in different shades of red to show Respiratory Irritation Index.

Courtesy of Research Article.



Respiratory irritation index for each bloom year for Manatee and Sarasota counties, 2006-2018.

Fish and Wildlife Research Institute researcher Kate Hubbard, who co-authored the study, said the research highlights that the cycles and severity of blooms change. And understanding this better will help answer the question of whether blooms are getting worse or not.

“So I don’t have a definitive answer, but I think it’s a really helpful step forward, because there are so many different ways to describe gravity,” she said. “And this effort kind of attacks that and says that’s how we’re going to define it here.”

Barbara Kirkpatrick, senior adviser for GCOOS and co-author, said she thinks the bloom lasts longer and that climate change could exacerbate it.

“What we think is yes, that these blooms last longer… Karenia brevis is a very old organism that existed with the dinosaurs, so it’s probably going to adapt very well to climate change and potentially outperform d “other creatures in the water, potentially causing more blooms. I know people don’t want to hear that, but it’s the truth,” she said.

“What we know for sure is that the more people that come to our shoreline and populate our shoreline, the more people are affected by these blooms.”

Bar graph of bloom severity between 1953 and 2019.

Courtesy of Research Article.



Bloom Severity Index.

However, Kirkpatrick said it’s actually very difficult to find solid trends in red tide data.

“Our detection methods are constantly improving. And why it’s sort of…bad news is just because we haven’t had the same set of data for, say, 30, 40, 50 years,” she said. “Techniques have changed, and that makes it really difficult to compare decade to decade.

Kirkpatrick said scientists will soon look at the 2021 red tide bloom that has affected Florida’s southwest coast — including Tampa Bay — for months as part of the study’s findings. And they hope to eventually use the clues to help predict and prepare for future blooms.

“With these new indices, not only can we examine blooms historically using objective standards, but we can also apply the index to current blooms to give the public a better sense of risk – similar to how the National Weather Service developed the Heat. Index, the Climate Extreme Index and other indices,” said Richard Stumpf of NOAA-NCCOS in a press release.

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